Commit acb9f2d4 authored by Arnaldo Carvalho de Melo's avatar Arnaldo Carvalho de Melo
Browse files

perf evsel: Provide meaningful warning when trying to use 'aux_output' on older kernels 

Just like we do with the 'write_backwards' feature:

Before:

  # perf record -e {intel_pt/branch=0/,cycles/aux-output/ppp} uname
  Error:
  The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (cycles/aux-output/ppp).
  /bin/dmesg | grep -i perf may provide additional information.

  #

After:

  # perf record -e {intel_pt/branch=0/,cycles/aux-output/ppp} uname
  Error:
  The 'aux_output' feature is not supported, update the kernel.
  #

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/n/tip-wgjsjroe1e150c0metgwmqwd@git.kernel.org


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 243384dd

tools/perf/util/evsel.c

+9 −2
Original line number Diff line number Diff line
@@ -1738,7 +1738,8 @@ int evsel__open(struct evsel *evsel, struct perf_cpu_map *cpus, 
	int pid = -1, err;

	enum { NO_CHANGE, SET_TO_MAX, INCREASED_MAX } set_rlimit = NO_CHANGE;



	if (perf_missing_features.write_backward && evsel->core.attr.write_backward)

	if ((perf_missing_features.write_backward && evsel->core.attr.write_backward) ||

	    (perf_missing_features.aux_output     && evsel->core.attr.aux_output))

		return -EINVAL;



	if (cpus == NULL) {
@@ -1912,7 +1913,11 @@ try_fallback: 
	 * Must probe features in the order they were added to the

	 * perf_event_attr interface.

	 */

	if (!perf_missing_features.bpf_event && evsel->core.attr.bpf_event) {

	if (!perf_missing_features.aux_output && evsel->core.attr.aux_output) {

		perf_missing_features.aux_output = true;

		pr_debug2("Kernel has no attr.aux_output support, bailing out\n");

		goto out_close;

	} else if (!perf_missing_features.bpf_event && evsel->core.attr.bpf_event) {

		perf_missing_features.bpf_event = true;

		pr_debug2("switching off bpf_event\n");

		goto fallback_missing_features;
@@ -2926,6 +2931,8 @@ int perf_evsel__open_strerror(struct evsel *evsel, struct target *target, 
			return scnprintf(msg, size, "clockid feature not supported.");

		if (perf_missing_features.clockid_wrong)

			return scnprintf(msg, size, "wrong clockid (%d).", clockid);

		if (perf_missing_features.aux_output)

			return scnprintf(msg, size, "The 'aux_output' feature is not supported, update the kernel.");

		break;

	default:

		break;

tools/perf/util/evsel.h

+1 −0
Original line number Diff line number Diff line
@@ -184,6 +184,7 @@ struct perf_missing_features { 
	bool group_read;

	bool ksymbol;

	bool bpf_event;

	bool aux_output;

};



extern struct perf_missing_features perf_missing_features;

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